Warm air units

ABSTRACT

A warm air producing unit in which an airflow chamber and a tank for the bulk storage of liquid are both heated by a common combustion chamber is characterized in that part of the surface area of the tank is exposed directly to the heat generated in the combustion chamber so that the water in the tank may be heated, and part of the surface area of the tank is swept over by at least some of the airflow in the airflow chamber, the ratio of the two areas being such that when the combustion gases have heated the water in the tank to a predetermined temperature the heat loss from the contents of the tank to said airflow is sufficient to prevent said predetermined temperature from being exceeded.

United States Patent Inventor Mario M. Masrieh I Belle Vue, 21 Montacute Road, Lewes, Sussex, England Appl. No. 772,268 Filed Oct. 31, I968 Patented Feb. 16, 1971 Priority Aug. 8, 1968 Great Britain 37827/68 WARM AIR UNITS 4 Claims, I Drawing Fig.

U.S. Cl 126/101 Int. Cl F24d 5/10 Field of Search 126/ I01; 122/( AH References Cited UNITED STATES PATENTS 24,590 6/I 859 Spence 126/101 UX 1/1897 Pettibone etal us/101 x l,363,555 I2/l920 Beattie l26/I0l 2,269,055 l/l942 Gower I26/IOIX FOREIGN PATENTS 993,937 6/I 965 Great Britain I26/I0l Primary Examiner- Frederick L. Matteson Assistant Examiner- Robert A. Dua Anomey- Webster B. Harpman ABSTRACT: A warm air producing unit in which an airflow chamber and a tank for the bulk storage of liquid are both heated by a common combustion chamber is characterized in that part of the surface area of the tank is exposed directly to the heat generated in the combustion chamber so that the water in the tank may be heated, and part of the surface area of the tank is swept over by at least some of the airflow in the airflow chamber, the ratio of the two areas being such that when the combustion gases have heated the water in the tank to a predetermined temperature the heat loss from the contents of the tank to said airflow is sufficient to prevent said predetermined temperature from being exceeded.

" exposed directly-to the WARM n auu rs BACKGROUND or THE'INVENTION mal domestic requirements; (2) if sufficient hot water is not drawn off within a predetermined period, the waterin'the tank commencesto boil. I

This invention eliminates the above drawbacks by providing a combined warm air developing unit and bulk liquid storage tank in association with a common combustionchamber in such a manner that an adequate supply of hot water is always readily available but such that the water inthe tank will not boil. 1 1 v j I SUMMARY, OF THE INVENTION The warm air developing unit disclosed herein comprises a combustion chamber, one or more airflow chambers through which an airflow can be created, andfiatank forstoring a bulk supply of liquid, characterized in that part of the surface area of the tank is exposed directly to theheat generated .in the combustion chamber so that water in the tank may be-heated, and part of the surface area of the tank is swept over;by at least someof said airflow, the ratio of said areas being. such that when the combustion gases have heated therwater in the tank to a predetermined temperature the heat loss from the contents of the tank to said airflow is sufficient toprevent said predetermined temperature from being exceeded.

To ensure an adequate supply ofwarm air, one or more of said airflow chambers havesurfaces exposed directly to the heat generated in the combustion chamber.

Thus, the general principle of the present inventionis that a bulk hot water tank, for example of galvanized metal, is built into a combustion chamber of the. warm air unit, and at least part of the walls of this bulk-storage unit is, protected by at least one of the aforesaid airflow chambers; The surface area of the walls of the watertank that arepermitted to be heated directly by the burning gases in the combustion chamber; and the surface area of the walls of the water tankthat are shielded by said airflow chamber; are sorelated 'that a careful balance a is maintained between the flow of burning gases over the water tank and flow of hot air overthe water tank, to ensure been constructed to DESCRIPTIONOF THE DRAWING The drawings show a schematic cross-sectional view through one embodiment of a warm air developing unit incorporating a tank for the bulk storage of liquid.

DESCRIPTION OF THE PREFERRED EMBODIMENT As shown the warm air unit comprises a combustion chamber 1 in which is aflame rim 2. The burning gases 2A rising from the flame rim 2 pass up an annular-flue flow path 3 defined by an outer wall 3A and a further wall 3B and escape via a stack 4. I The annular-flue'flow path 3 surrounds an annular airflow chamber 5 to which air is supplied at the lower end chamber 5 defined by the outer wall 3A and an inner annual wall 5A and air is supplied at the lower end of chamber 5 by ducting 6 The air in the chamber 5 is heated by the burning or burnt gases 2A passing up the annular flow path 3 and eventually escapes via an outlet 7 where the heated air is distributed through suitable ducting'(not shown) to the point where hot air is required. a a y According to the invention the annular airflow chambers surroundsthe inner wall 5A which forms the vertical sides of a hot water tank 8, the tank 8 has an upper transversely extending wall-8A and a lower transversely extending wall 88 or base tank 8 being of sufficientvolume to accommodate a bulk supply of :hot water, for example to gallons depending uponthe size of the. warm air unit. It will be understoodfrom the drawing that the lower wall 8B OIlbZiSB, of the hot water tank 8 is exposed to the combustion gases in the combustion chamber 1, but that the inner wall 5A which forms the side walls of the water tank 8 are swept over by the air being drawn throughthe airflow chamber 5;

By suitably .proportioning the surface area of a the water tank 8 that is. exposed to the combustion chamber 1 as compared with the surface area of the water tank '8 that is surrounded by a the annular air flow chamber 5 containing air to be heated, it

' is'possible to predetermine the maximum temperature to that the water in the water tank shall be capable of reaching,

but not exceeding, a predeterminedmaximum temperature whilst the warm air blower is operating and the combustion ehamberisin operation. Y L..

The storage capacity of the, tank'and enact the tank that is exposed directly to the heat generated in the combustion chamber are such as to provide a supply of hot water sufficient to meet the demands of a predetermined domestic requirement. 7

There may be two airflow chambers arranged one inside the other, such that there is a space between said airflow chambers through which the combustion gases can flow to heat air,

passing through said airflow chambers. In this construction the inner wall of the inner airflow chamber surrounds some of the water in said tank. a

The two airflow chambers may each be of annular shape, the inner wall of the inner airflow chamber having upper and lower closures such that at least-some of said inner wall and said upper and lower closures cooperatetofdeflne said tank. In this construction it is the lower closure'of the tank that may be heat generated in the combustion chamber. I 1

which the water in the storage tank is capable of being raised under normaloperating conditions, for example 90 C. Thus, when cold water is present in thetank 8, it receives heat not only from the direct action of the combustion gases on the louver, wall 88 of the water tankj8, but it receives heat also from 'the'hot air circulating through the annular airflow chamber 5 and against the inner wall SA-thereof, thus ensur ing a rapid rise in temperature of the water in the water tank 8.

I When the temperature of the water in the tank 8 commences to rise abovethe temperature of the air flowing through the airflow'chamber 5, then the water in the tank 8'commences to give up some of its heat to the airflowing through the airflow chamber 5. Thus, eventually, a static state is reached at which the exchange of heat from the water in the tank 8 to the air flowing through the annular airflow chamber 5 is equal to the rate at which heat is being transmitted to the water via the lower wall 88 of the water tank 8 When this occurs the water predetermined maximum temannular airflow chamber 9 defined by a casing 9A surrounds the'flow path 3 for the burning or burnt gases. Thus, the burning or burnt gases passing up the flow path 3 transmit heat to I both the chamber 5 and the chamber 9, both chambers receiving air at their lower ends by means of a blower 11 mounted at the base of the unit and passing hot air out via exits 7 and 10 respectively. The blower 11 is illustrated as being below the combustion chamber.

The efficiency of the air heating unit is enhanced by having the flame rim 2 of such size that the flames rising therefrom are adjacent to the inner wall of the outer airflow chamber 9.

The water tank 8 may be fitted with an electrical immersion heater for use during the summer months and may be so wired electrically that it is impossible for said immersion heater to be energized when the flame rim 2 is in operation.

Having now described one embodiment of the present invention it will be appreciated that the combustion chamber 1 may be fired by any suitable means and that said means is not necessarily the aforesaid flame rim 2.

It will also be appreciated that whereas in the particular embodiment illustrated, only the base of the water tank 8 is exposed to the combustion gases and the remainder of the water tank 8 is screened by the airflow chamber 5, this is by way of example only and any other suitable surface areas may be so heated and screened in order to achieve the desired maximum temperature of the water in the water tank 8 under normal operating conditions of the warm air unit.

Thus, whilst only one particular embodiment of the present invention has been illustrated and described, it will be apparent to those skilled in the art that various changes and modificatons may be made therein without departing from the spirit of the invention, and having thus described my invention.

I claim:

1. A warm air developing unit comprising inner and outer walls defining between them an upwardly extending annularshaped airflow passage, the inner wall of said airflow passage having spaced apart transversely extending upper and lower walls defining between them in association with said inner wall a tank for storing a bulk supply of water, a further wall defining a combustion chamber surrounding said outer wall and depending below said lower transversely extending wall such that the combustion gases generated below said lower transversely extending wall can act directly on said lower transversely extending wall, the space between said outer wall and said further wall acting as a flow path for the combustion gases around the annular-shaped airflow passage, air inlet ducting passing through said further wall to the airflow passage, and an air outlet opening in the unit permitting air to escape from the upper end of said airflow passage, the surface area of the tank that is surrounded by said airflow passage being such that when the water in thetank has been heated to a predetermined temperature by the combustion gases the heat loss from the water in the tank to the air flowing through said airflow passage is sufficient to prevent said predetermined temperature from being exceeded.

2. A warm air developing unit as claimed in claim 1 and including an upwardly extending outer'casing surrounding and spaced from said further wall to form a further airflow passage.

3. A warm air developing unit as claimed in claim 2 and wherein said air inlet ducting passes through said further wall to communicate with said further airflow passage.

4. A warm air unit as claimed in claim 2 and wherein the air outletopening receives air from the airflow passage and the further airflow passage. 

1. A warm air developing unit comprising inner and outer walls defining between them an upwardly extending annular-shaped airflow passage, the inner wall of said airflow passage having spaced apart transversely extending upper and lower walls defining between them in association with said inner wall a tank for storing a bulk supply of water, a further wall defining a combustion chamber surrounding said outer wall and depending below said lower transversely extending wall such that the combustion gases generated below said lower transversely extending wall can act directly on said lower transversely extending wall, the space between said outer wall and said further wall acting as a flow path for the combustion gases around the annular-shaped airflow passage, air inlet ducting passing through said further wall to the airflow passage, and an air outlet opening in the unit permitting air to escape from the upper end of said airflow passage, the surface area of the tank that is surrounded by said airflow passage being such that when the water in the tank has been heated to a predetermined temperature by the combustion gases the heat loss from the water in the tank to the air flowing through said airflow passage is sufficient to prevent said predetermined temperature from being exceeded.
 2. A warm air developing Unit as claimed in claim 1 and including an upwardly extending outer casing surrounding and spaced from said further wall to form a further airflow passage.
 3. A warm air developing unit as claimed in claim 2 and wherein said air inlet ducting passes through said further wall to communicate with said further airflow passage.
 4. A warm air unit as claimed in claim 2 and wherein the air outlet opening receives air from the airflow passage and the further airflow passage. 